This invention relates to a dash panel structure for an automobile. More particularly, the invention relates to a skin material for an instrument panel incorporating a surface layer of virgin material of predefined color and an interior layer of regrind material for disposition in overlying relation to the door panel for an inflatable air bag cushion. A method of manufacturing such skin material is also provided.
It is well known in motor vehicles to provide an air bag module which includes an inflatable air bag cushion for the protection of a vehicle occupant in the event of a collision. The air bag module typically includes an inflator for discharging an inflation medium such as high pressure gas or the like into the air bag cushion upon the occurrence of a predetermined level of vehicle deceleration or other measurable vehicle condition.
Inflatable air bag cushions may be disposed at a number of locations within the vehicle so as to provide protection for the occupants therein during various collision events. In particular, it is known to utilize an inflatable air bag cushion stored within the hub of the steering wheel for protection of the operator of the vehicle and to utilize an inflatable air bag cushion deployable from the dash panel for protection of a passenger within the vehicle during a collision event.
In order to facilitate the deployment of inflatable air bag cushions from the dash panel, it is known to incorporate a tear pattern partially across an outer skin layer forming the show surface of the dash panel in the region over the air bag cushion. This tear pattern preferentially tears to form a desired deployment opening pattern at a defined location across the surface of the dash panel as the air bag cushion is inflated. The materials forming the outer skin layer are typically thermoplastic polymers of substantial resiliency such as thermoplastic polyolefin (TPO) and polyvinyl chloride (PVC). In the typical manufacturing process, the outer skin layer is of a single layered construction overlying a resilient foam material. The foam and skin are typically supported across an underlying substrate door panel of frangible character to permit egress of the underlying air bag cushion. The material forming the outer skin layer typically includes a colorant to impart a predefined coloration across the surface of the dash panel.
During the typical manufacturing process, the outer skin layer is in the form of a single layered sheet extruded to a desired thickness from virgin stock material of a particular color. The single layer sheet is thereafter transferred to a vacuum mold for shaping to the desired profile geometry for the dash panel. During the vacuum molding process, excess material is trimmed away and discarded. The foam layer may thereafter be cast across the underside of the molded skin to form a foam backed composite. Prior to application of foam, the interior surface of the outer skin layer may be scored to a predefined depth in a pattern corresponding to a breakout pattern forming a deployment path for the underlying air bag cushion.
As will be appreciated, the vacuum forming and trimming of the polymer sheet to form the outer skin layer to the desired configuration may generate a substantial quantity of waste material. Heretofore, this waste has generally been discarded. The practice of discarding such material may give rise to added cost both in terms of the need to purchase larger volumes of virgin skin-forming material as well as in the cost associated with the proper disposal of the portions of the skin material which are not used.
The present invention provides advantages and alternatives over the prior art by providing a skin layer for disposition in overlying relation to an air bag cushion assembly. The skin layer is of a multi-layered construction including a top layer of virgin (i.e. non recycled) polymeric material forming a show surface of controlled predefined color across the vehicle dash panel and an underlying layer of regrind material formed from scraps of material generated during molding and trimming of the dash panel covers. The scraps may be of different colored materials. A tear seam may be scored across the underside of the skin extending into the underlying layer of recycled material in a desired break-out pattern for the air bag cushion. The skin layer may be disposed across an underlying layer of foam which in turn is disposed across a supporting panel structure.